Genetic Risk Factors and Inhibitor Development in Hemophilia: What Is Known and Searching for the Unknown.

Over the past few decades, important knowledge on why inhibitors develop and better information about significant risk factors have become available. A series of both genetic and nongenetic factors are recognized and clinical score systems were proposed to quantify the risk for each patient. In addition, modulation of the immunological response was acknowledged to play a pivotal role in the occurrence of inhibitors. However, with the exception of mutation testing in severe hemophilia B patients, no single risk factor or clinical score is currently utilized in clinical practice. "Omics" technologies are large-scale hypothesis-generating approaches, which provide the tools to study issues contributing to a complex and multifactorial phenomenon, such as inhibitor development. Newer cutting edge technologies may enable a more accurate estimation of the personal risk profile and provide a reliable tool to accurately measure the risk periodically, thereby enabling strategies to foresee and prevent inhibitor formation.